JPH0546032U - Wire bonding equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] The object is to obtain a wire bonding apparatus capable of performing stable wire bonding that suppresses a temperature difference between die pad positions on the surface of a heat coma and preventing quality variations between products. [Structure] On a heat block 11 in which heaters 12 and 12 are built in parallel to a longitudinal direction, a heat piece 13 having a groove 13a formed on a lower surface is placed, and wire bonding is performed on the heat piece 13. Since three lead frames 14 are placed on the upper surface of the heat piece 13, and the die pad 14 of the lead frame 14 is located at the positions a, b, and c, the heat of the heater 12 is substantially formed by the groove 13a. Uniform heat transfer, uniform heating temperature, stable wire bonding, and uniform product quality.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a wire bonding apparatus, and more particularly to heating means for wire bonding a lead frame having a plurality of die pad portions formed in series.

[0002]

[Prior Art]

 Conventionally, as this type of wire bonding apparatus, one provided with a heating means as shown in FIG. 5 is known. In this heating means, as shown in the figure, a cylindrical heater 2 is inserted along the longitudinal direction of a heat block 1 made of SK S, and a stainless steel heat piece 3 is placed on the heat block 1. Through the heat piece 3, the lead frame 4 having the die 5 mounted on the die pad portion is heated to 200 ° C. or higher. Then, an electrode of the chip 5 and the lead portion 4a of the lead frame 4 are wire-bonded to each other in such a heated state by a wire supply mechanism (not shown). As another device of this type, a semiconductor assembling device described in JP-A-56-140638 is known.

[0003]

[Problems to be solved by the device]

 However, in the wire bonding apparatus having the above-mentioned conventional heating means, there is a problem that a temperature difference occurs on the surface of the heat piece 3 depending on how the heat is transferred from the heat block 1.

FIG. 6 is an explanatory view of the AA cross section of FIG. 5, and shows a distribution showing a heat transfer state from the heater 2. In FIG. 6, when the lead frame 4 shown in FIG. 5 is placed on the surface of the heat piece 3, the temperature difference becomes large at the positions a, b, and c where the three consecutive die pads are placed, and the die pad portion during wire bonding is There was a problem that the heating temperature became uneven and stable bonding could not be performed.

Further, as shown in FIG. 7, even when two heaters 2 and 2 are built in the heat block 1 in parallel, the temperature distribution in the cross section of the heat piece 3 is as shown in FIG. As is clear from the graph shown in FIG. 8, a temperature difference of 3 ° C. occurs between a and b, and a temperature difference of 3 ° C. occurs between b and c, and uneven heating temperatures are inevitable.

The present invention was devised with these problems in mind, and can perform stable wire bonding that suppresses the temperature difference between the die pad positions on the surface of the heating coma, and prevents variations in product quality. The purpose is to obtain a wire bonding device that can

[0007]

[Means for Solving the Problems]

 Therefore, the present invention is a wire bonding apparatus having a heat block having a built-in heater and a heat coma mounted on the heat block and conducting heat from the heat block. The solution is to form a thermal gap that controls the surface temperature of the heat coma substantially uniformly.

[0008]

[Action]

 The thermal gap formed between the heat coma and the heat block corrects the non-uniformity of the temperature of the heat block surface heated by the heater, and makes the surface temperature of the heat coma substantially uniform. Therefore, the heating temperature between the plurality of die pads of the lead frame mounted on the heat piece is substantially equalized, and stable wire bonding becomes possible.

[0009]

【Example】

 The details of the wire bonding apparatus according to the present invention will be described below with reference to the embodiments shown in the drawings.

First Embodiment FIG. 1 is an explanatory view of a cross section of a main part of the first embodiment. As shown in the figure, the wire bonding apparatus 10 of the present embodiment includes a heat block 11, two heaters 12 incorporated in the heat block 11, a heat comma 13 placed on the heat block 11, The bonding means for performing wire bonding to the lead frame 14 on which the chip 15 mounted on the heat piece 13 is mounted is generally constituted by means 16.

The heat block 11 has substantially the same shape as the conventional one shown in FIGS. 5 and 6, and a step portion 11 a on which the heat piece 13 is placed is formed on the upper surface thereof. Further, the two heaters 12 are heated so that they are located at positions a, b, and c between positions a, b, and c where the die pad of the lead frame 14 mounted on the heating piece 13 is formed and between b and c. The blocks 11 are arranged in parallel with each other in the longitudinal direction.

The heat piece 13 is formed with a recess so that the lower surface is closely fitted to the stepped portion 11 a of the heat block 11, and the lower surface around the recessed portion has a predetermined distance from the upper surface of the non-stepped portion 11 a of the heat block 11. Is set to keep. Further, a groove 13a serving as a thermal gap is formed in the center of the lower surface along the longitudinal direction. The width of the groove 13a is set to be slightly wider than the width of the die pad of the lead frame 14 placed at the position b of the heat piece 13. Therefore, the heat from the two heaters 12, 12 is transferred to the upper surface side of the heat piece 13 through the heat block 11 from the lower surface portions 13b and 13c divided by the groove 13a of the heat piece 13. The curve drawn on the heater frame in FIG. 1 is an isotherm (in increments of 1 ° C.), indicating that the closer to the heater 12, the higher the temperature. FIG. 2 is a graph showing the temperature distribution in the width direction on the upper surface of the heat piece 13. The temperature of the lead frame die pads a, b, and c placed on the heat piece 13 falls within the range of 290 to 291 ° C. , Shows that they are almost uniform. This is because the groove 13a, which is a thermal void (in this case, the thermal conductivity is significantly smaller than the material of the heat piece 13), is formed immediately below the position b, so that the temperature at the position b shown in the graph of FIG. The rise is suppressed, and the temperature is made uniform between the die pad positions of the lead frame 14 (the positions where wire bonding is performed). In this embodiment, air is present in the groove 13a, and this air has a low heat transfer efficiency. However, a material having a low heat conductivity may be filled in the groove 13a.

Further, in this embodiment, the groove 13a is formed in the center of the lower surface of the heat piece 13 as a thermal gap, but the groove is not formed in the heat piece 13 and a material having a low thermal conductivity is used as the heat piece 13. It may be configured to be embedded inside.

Second Embodiment FIG. 3 is an explanatory view of a cross section of a main part of the second embodiment, and the configurations of the heat block 11 and the heaters 12 and 12 are the same as those of the first embodiment described above. is there. The shape of the heat piece 13 is also substantially the same as that of the first embodiment, but in this embodiment, two grooves 13A and 13B are formed on the lower surface along the longitudinal direction of the heat piece 13 to form the heat block 11. The three heat transfer surfaces 13C, 13D, 13E which contact are formed. The heat transfer surface 13C is formed right under the position a of the die pad of the lead frame placed on the upper surface of the heat piece 13, the heat transfer surface 13D is formed right under the position b, and the heat transfer surface 13E is formed right under the position c. .. The width of the heat transfer surface 13D is set to be slightly smaller than that of the heat transfer surfaces 13C and 13E because the amount of heat conduction from both heaters 12 and 12 is large. In FIG. 3, the curve drawn on the heat piece 13 is an isotherm (in increments of 1 ° C.), and the heat transfer from the heat transfer surfaces 13C, 13D, 13E to the upper surface of the heat piece 1 is similar. I understand.

Further, the graph shown in FIG. 4 shows the result of measuring the temperature of the surface of the heat piece 13 in the width direction, and it can be seen that the positions a, b, and c are at substantially the same temperature. ..

Also in this embodiment, the same action and effect may be obtained by filling the grooves 13A and 13B with a material having a low thermal conductivity, or by embedding a material having a low thermal conductivity in the heat piece 13. You can get fruit.

Although the embodiment has been described above, the present invention is not limited to this, and various design changes associated with the gist of the configuration can be made.

For example, in both of the above embodiments, the thermal gap is formed on the heat coma side, but it may be formed on the heat block side.

The number of thermal voids is also changed according to the number of die pads of the lead frame.

[0020]

[Effect of the device]

 As is clear from the above description, according to the wire bonding apparatus of the present invention, it is possible to suppress the heating temperature difference between the positions where the die pad is placed on the surface of the heat piece, and it is possible to perform stable wire bonding. This has the effect of reducing variations in quality between products.

Further, according to the present invention, it is possible to achieve easy temperature setting and management.

[Brief description of drawings]

FIG. 1 is an explanatory view of a cross section of a main part of a first embodiment of the present invention.

FIG. 2 is a graph showing the temperature distribution in the width direction on the surface of the heat piece of the first embodiment.

FIG. 3 is an explanatory view of a cross section of a main part of a second embodiment of the present invention.

FIG. 4 is a graph showing a temperature distribution in the width direction on the surface of the heat piece of the second embodiment.

FIG. 5 is a perspective view of a conventional wire bonding device.

6 is a cross-sectional view taken along the line AA of FIG.

FIG. 7 is an explanatory view of a cross section of a main part of another conventional example.

FIG. 8 is a graph showing a temperature distribution in the width direction on the surface of a heat coma of another conventional example.

[Explanation of symbols]

10 ... Wire bonding device, 11 ... Heat block, 12 ... Heater, 13 ... Heat coma, 13a ... Groove (thermal gap), 14 ... Lead frame.

Claims (1)

[Scope of utility model registration request] 1. A wire bonding apparatus having a heat block containing a heater and a heat piece mounted on the heat block for conducting heat from the heat block, wherein the wire bonding apparatus is provided between the heat piece and the heat block. A wire bonding apparatus, wherein a thermal gap is formed to control the surface temperature of the heat coma substantially uniformly.